UK Supreme Court Rule In Favour Of Biological Sex In Definition Of A Woman

By Chloe Jacob

The UK Supreme Court has unanimously ruled in favour of defining the legal definition of woman and sex to be in line with biological sex and gender assigned at birth, leaving transgender women with gender recognition certificates outside of this legal definition. This means transgender women with a gender recognition certificate (GRC) can be excluded from single-sex spaces if “proportionate”, including public restrooms, female support groups, female gyms and leisure centre areas and prisons [1].

The ruling comes after tireless campaigns from Scottish campaign group For Women Scotland to redefine sex-based protections to only centre around biological sex. This ruling has stirred enormous amounts of fear and vulnerability within the UK transgender population, and joy from members of For Women Scotland, with members screaming with joy, hugging and punching the air in celebration. The dichotomy of reaction characterises the fervent misalignment of belief in a transgender person’s right to protection based on sex alone.

The Scottish government has campaigned in disagreement with For Women Scotland, stating that due to the Gender Recognition Act of 2004, certified sex is in fact the determining factor for sex-based protections, not biological sex. This, however, was surpassed by the Supreme Court, as they ruled that the context of the word sex in the 2010 Equality Act does not include certified sex – despite the former acts’ antecedent nature. The Government in court fervently rebutted this ideology stating that within the confines of the law, that certified sex is legal sex for all purposes, but to little avail.

The Supreme Court has attempted to remove the partisan nature of this ruling in stating “We counsel against reading this judgement as a triumph of one or more groups in our society at the expense of another, it is not.” [1] This statement is in referral to their claims that the law still protects transgender women from discrimination. The community has responded in dismay, making the point that while transgender women are protected from discrimination for their trans identity, they are no longer protected from discrimination for their aligned sex – which is female.

Founder of For Women Scotland, Susan Smith has said in response to the ruling “Sex is real and women can now feel safe that services and spaces designated for women are for women and we are enormously grateful to the Supreme Court for this ruling” [1]. The trans community across the UK has found it difficult to align with the Supreme Courts statement that this is not a triumph over one specific group considering the inflammatory comments made by For Women Ireland, that are indicative of the belief that having transgender women in female spaces is equivalent to a lack of safety for biological women in these spaces. Notable names in support of this ruling include JK Rowling, who has been known to associate with anti-transgender litanies and propaganda. Scottish Green MSP Maggie Chapman, a prominent campaigner for trans-rights has stated that “This is a deeply concerning ruling for human rights and a huge blow to some of the most marginalised people in our society.”

Echoes of agreement with this ruling have popped up across the island of Ireland, with a notable and unexpected addition of Sinn Fein TD David Cullinane weighing in on the matter. The TD stated that the ruling was one of “common sense”, and that it should be examined within the context of Irish legislation also [2].

The Waterford TD faced enormous backlash for his comments on social media, particularly from his constituent community, with groups such as Pride of The Déise, an LGBT community within Waterford, calling for him to retract his statements with an apology. The group has provided useful statements, combatting the sentiment of For Women Scotland. The group has characterised his information as anti-science, clarifying that the definition of sex as biological is complex and not binary, due to the existence of intersex individuals. They also clarify that gender is a social and legal construct, entirely separate to that of biological sex.

David Cullinane is Sinn Féin’s spokesperson on health, leading to further concern about his comments made on this issue. The TD’s comments are directly misaligned with Sinn Féin’s ideology associated with gendered protection, and thus many in the community felt mislead in their votes toward him in the most recent general election. The TD has since removed all comments from social media and has publicly apologised for any hurt caused [2]. People Before Profit TD Ruth Coppinger asked if Mr Cullinane was reflecting the official Sinn Féin policy position and this was mirrored by a multitude of opposition party members. Sinn Féin has stated that due to Cullinane’s apology, there is nothing more to say on the matter, providing little insight as to whether they support his statement about an examination of the application of this law to Irish society is mirrored by the party.

This policy has created a massive vulnerability for trans people within our communities, and while the idea that this should be extended into Irish society has been bandied within conversation, all major political parties in government and opposition in the country are not aligned with this idea. Transgender rights campaigners have said that while this is a “massive blow” to transgender progress, it is not the end of their fight for equal rights and treatment within their legally protected sex.

References

[1] Cochrane, A., (2025). “Supreme Court to Announce Ruling on Definition of a Woman.” BBC News, 15 Apr 2025. https://www.bbc.com/news/articles/cvg7pqzk47zo

[2] McGee, H., (2025). “Sinn Féin Health Spokesman David Cullinane Backtracks on Comments Welcoming UK Ruling Defining the Term
‘Woman.’” The Irish Times, 17 Apr 2025. https://www.irishtimes.com/politics/2025/04/17/sinn-fein-health-spokesman-david-cullinane-backtracks-on-comments-welcoming-uk-ruling-defining-the-term-woman/

[3] RTE.ie. (2025). “Mixed Reaction to UK Court Ruling on Biological Sex.” RTÉ, 16 Apr 2025. https://www.rte.ie/news/uk/2025/0416/1508061-reaction-to-uk-sex-ruling/